This invention relates generally to ball valve couplings of the type having an identical pair of ball valve units adapted for releasible connection in in-line, face-to-face relation, for use in fluid handling or fluid transfer applications. More specifically, this invention relates to an improved ball valve coupling having lock-out means for preventing valve opening unless the ball valve units are fully and properly engaged in fluid-sealed relation, and for preventing disassembly of the ball valve units unless the valves are closed.
Ball valve couplings are generally known in the art for use in releasible in-line connection of a pair of fluid flow conduits. The ball valve coupling typically comprises a pair of ball valve units adapted for mounting onto the ends of a pair of fluid flow conduits, wherein the ball valve units in turn include quick connect coupling members to accommodate relatively rapid and easy interconnection in fluid-sealed relation. The thus-assembled ball valve units additionally include a corresponding pair of rotatable ball valves movable between closed and open positions for correspondingly preventing and permitting fluid flow. A variety of ball valve configurations have been proposed in the prior art, with a view toward reducing or eliminating significant residual volume between the ball valves in the closed positions, thereby reducing or eliminating undesired fluid spillage when the ball valve units are disassembled. Ball valve couplings of this general type are used in a wide range of fluid handling applications, particularly such as a fuel handling environment.
In recent years, considerable design emphasis has focused upon ball valve couplings of a so-called sexless or unisex geometry wherein two matching or identical ball valve units are provided for relatively quick and easy releasible interconnection in an in-line, face-to-face relation. The provision of a sexless ball valve coupling beneficially ensures that any two ball valve units in a fluid handling environment may be assembled and disassembled quickly and easily, without limiting the assembled coupling to traditional male-female structures. In addition, such sexless couplings have included safety features intended to minimize fluid spillage attributable to attempted fluid flow prior to full and proper sealed interconnection of the ball valve units, or attempted disassembly of the ball valve units prior to full closure of the ball valves. See, for example, U.S. Pat. No. 4,438,779 which discloses a sexless ball valve coupling wherein each ball valve unit includes an extensible safety pin which moves with the associated ball valve in a manner intended to prevent ball valve opening unless a pair of ball valve units are fully engaged, and to prevent disassembly of the ball valve units unless the respective ball valves are closed. While safety features of this type have provided an advance in the construction and operation of sexless ball valve couplings, the requirement for coordinated concurrent movement of the safety pin and the ball valve can, in some failure modes, permit partial opening of the ball valve before improper connection of the ball valve units is detected. This creates a risk of fluid leakage, wherein such fluid leakage is highly undesirable in some applications such as fuel handling environments.
There exists, therefore, a significant need for further improvements in ball valve couplings of the so-called sexless type, particularly with respect to providing a substantially failsafe lock-out means for preventing ball valve movement to an open position unless a pair of the ball valve units are fully engaged, and for preventing disassembly of the ball valve units unless each ball valve is fully closed. The present invention fulfills these needs and provides further related advantages.